Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 180927

Area Forecast Discussion
National Weather Service State College PA
427 AM EST Thu Jan 18 2018

A large are of high pressure centered over the Lower Mississippi
Valley will ridge northeast across the Ohio River Valley and
into the Mid Atlantic states today. This weather feature will
maintain fair skies but cold temperatures. Temperatures will
moderate to near normal Friday, then climb well above normal
over the upcoming weekend with mainly dry weather continuing.
The next chance for widespread rain showers will come Monday
into Tuesday with the passage of a cold front.


GOES16 and regional sfc obs indicates a shallow layer of
orographic stratus and stratocu located near and to the west of
the Route 219 corridor (along the spine of the Alleghenies)
early this morning.

Model soundings show this cloud layer occupying the thermal
channel of -12 to -18C, which is right in the middle of the
prime Dendritic Growth Zone. We see confirmation of this with
some very light...4SM -snow being reported at KJST. Flurries
from this cloud layer are expected through 17Z today before
temps warm by several deg C in this layer and mixes out a bit.

Over the Central and Eastern parts of our CWA today, mainly
clear skies and light wind allowed temps to dip into the single
digits, and even near or slightly below zero F throughout some
protected valley locations across the Middle Susq Valley where a
deep fresh snowpack is found.

Later on and elsewhere today, periods of sct-bkn altocu and
cirrus will spill southeast from the glakes as deep layer warm
advection begin with the slow departure of the anomalously
deep, snow-producing sfc and upper low near the Outer Banks.

Highs this afternoon will be about 5 deg F below normal, and
range from near 20F across the NW mtns to the L30s in the
Southeast. Westerly winds will freshen to 10 to 15 kts today,
with gusts in the 25 to 30 kts range later this morning and this
afternoon over the higher terrain of SC and SW PA. Relatively
lighter winds will occur across the eastern zones.

The wind will create a wind chill 15 to 20 degrees F lower than
the actual air temp through today.


Variable amounts of mainly mid and high clouds along with dry
conditions will prevail tonight. A slightly lighter westerly
breeze with significantly lower gusts will result in wind chills
staying steady (or rising slightly) into tonight.

Lows tonight will be in the teens, to near 20F in the southern
PA valleys.

Mid and high clouds increase a bit Friday as do temps, that will
climb to slightly above normal highs.


High pressure moving off the southeast coast late in the week
will bring mild and dry weather to the area which will last
through most or all of the upcoming weekend.

A deep low will swing a cold front across the area late Monday
and early Tuesday next week, accompanied by a few period of rain
showers amounting to 1 to 3 tenths of an inch of Liq Equiv
precip. There is a low probability for a weak wave of low
pressure to develop along the front heading into Tuesday which
could add a few to svrl tenths more and even some light accums
of snow.

Mainly dry weather with just some isolated to scattered snow
showers will follow for Tuesday and Wednesday, with temps
falling to a few deg below normal by the middle of next week.


Lingering IFR continues to fade as the low levels dry out. This
will allow for improving conditions towards morning. The strong
gradient that is bringing the drier air will allow for a period
of LLWS to the region. Though the wind direction will be within
30 degrees, the speed shear will be well above 30kts. This will
continue the longest at the western TAF sites, where the central
and eastern TAF sites will improve by late Thursday morning.
 Once the inversion mixes late this morning, it will be breezy
with gusts in the 10-20 mph range.


Thu...Mainly VFR. Breezy.

Fri-Sun...Mainly VFR.

Mon...Reduced conditions with rain showers associated with an
approaching cold front.


The threat of ice jamming is diminishing. Dry and colder
weather into mid week will form additional ice as stream flows
and open channels decrease. Another warm up is expected by the
end of the week into the weekend with rain to accompany a
frontal system early next week. Dewpoints not fcst to be as
high as last Friday evening, so expecting less rain and runoff.




NEAR TERM...Lambert
SHORT TERM...Fitzgerald/Lambert
LONG TERM...Lambert/Martin
AVIATION...La Corte/Ceru
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